Stockholders' Equity - Additional Information (Detail) (USD $) Share data in Millions, unless otherwise specified	1 Months Ended	3 Months Ended			9 Months Ended
	Oct. 15, 2012	Sep. 30, 2013	Mar. 31, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Allocated share based compensation expense		$ 9,256,000		$ 37,817,000	$ 65,066,000	$ 267,124,000
Stock repurchase program authorized amount	200,000,000
Stock repurchase program number of shares repurchased					3.4
Payments for repurchase of common stock					9,302,000
Stock repurchase program remaining authorized repurchase amount					178,900,000
Treasury stock shares retired			31.3
Treasury stock retired cost method amount			297,600,000
ZSUs [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares granted as part of our executive compensation plan		9.7			9.7
Reversal of allocated share based compensation expense		3.7
Allocated share based compensation expense					$ 2,400,000